Modifications of ZnO thin films under dense electronic excitation

Spray pyrolyzed ZnO films prepared using solution containing ethanol and water (volume ratio 1:1), exhibited optical transmission of 85% in the visible range and electrical resistivity of 78 Omega cm. These samples were irradiated using 120 MeV Au ion beam and then characterized using optical absorption and transmission, x-ray diffraction (XRD), electrical resistivity measurements, x-ray photoelectron spectroscopy (XPS), and photoluminescence studies. It appears that irradiation does not affect absorption edge while optical transmittance was slightly reduced. But intensities of peaks of XRD and photoluminescence were found to decrease continuously with increasing ion fluence. Electrical resistivity of the films decreased considerably (from 78 to 0.71 Omega cm) with increase in ion fluence. Atomic concentration from XPS analysis showed that Zn/O ratio is getting increased due to ion beam irradiation. Variations in carrier concentration were also measured using Hall measurements. (C) 2005 American Institute of Physics.